What is a Molar Pregnancy?
A molar pregnancy is a very rare complication of pregnancy. It occurs when something goes wrong during the fertilisation process, and is caused by an abnormal cell growth of all or part of the placenta.
- A molar pregnancy is a very rare complication of pregnancy.
A molar pregnancy is not caused by anything you or your partner does or does not do.
In a normal pregnancy the fertilised egg is made up of 23 of the mother’s chromosomes and 23 of the father’s chromosomes.
In a complete molar pregnancy the egg contains no maternal chromosomes and only the 23 paternal chromosomes, meaning there is no fetus or amniotic sac present. The placenta is abnormal and develops rapidly with cysts present. These cysts grow in clusters like grapes and are visible by ultrasound.
A partial molar pregnancy occurs when there are 23 chromosomes from the mother and double from the father, making 69 chromosomes rather than the normal 46.This can occur because two sperm enter the egg and fertilise it or the sperm replicates itself once inside the egg. There will be some normal placental tissue amongst the abnormal cells and an embryo does develop. This may be a fetus or fetal cells but is genetically abnormal and not compatible with life.
This can often be a very upsetting time but so long as you get the right treatment and you are followed up routinely by the medical team then there should be no problem with physical health in the future. A molar pregnancy is also not caused by anything you or your partner does or does not do.
How common is a molar pregnancy?
About 1-3 in 1000 pregnancies in the UK results in a molar pregnancy. However, the incidence in Southeast Asian and Mexican women are higher. This raised level is unexplained at present.
What are the possible risk factors to having a molar pregnancy?
A molar pregnancy is thought to be caused by a problem with the genetic information from either the sperm or the egg. Factors that may increase your risk of having a molar pregnancy are:
- Women who are under 20 yrs or older than 35 yrs (risk steadily after 35 years) increases
- Women with a previous history of a molar pregnancy, particularly if they have had more than two.
- Women who have a low carotene intake (form of vitamin A). Women who have a diet low in carotene have a higher incidence of a complete molar pregnancy.
- Possible ovulatory disorders
- Ethnicity (as mentioned before women from Southeast Asia and also Native American women).
Little is known as to how and why molar pregnancies occur, therefore it is difficult to prevent. A good well balanced diet is recommended to help in the prevention.
Treatment of a molar pregnancy
Once a molar pregnancy has been diagnosed it is standard procedure to offer a D&C (dilatation and curettage) or an ERPC (evacuation of retained products of conception). These are types of surgical evacuation to remove all the abnormal cells. A sample of the removed tissue will be sent to the laboratory for examination.
It might take several days for the diagnosis to be confirmed. After this procedure you will be referred to a specialist unit to be monitored. The unit will monitor your HCG levels (pregnancy hormones) to make sure that they are decreasing, which is the sign that there is no abnormal tissue left.
It is important to monitor you for at least six months after the pregnancy as tiny cells of the molar pregnancy can spread and grow quickly for up to several months after.
Less than 15% of women who have a molar pregnancy will go onto develop persistent gestational trophoblastic disease which is when abnormal cells remain after the abnormal tissue has been removed. These women will require a course of chemotherapy and be monitored closely to make sure that the cells have not spread. It should not affect your chances of having a child in the future.
What about future pregnancies?
The outlook for future pregnancies is good. The risk that a mole will develop in a future pregnancy is about 1-2%.
If the treatment has been a D&C or ERPC and monitoring the hCG levels then it is advised to avoid pregnancy for six months starting from the time the hCG levels in your urine are normal.
For the women that have had the additional treatment with medication it is best to wait one year from the point of treatment finishing.
For similar hormonal reasons, use of the oral contraceptive pill is not recommended until the hCG levels are normal. It may take a few months for your periods to return to normal.
More information and support
If you have, or someone you know has, suffered a molar pregnancy, and would like additional support, please visit the In Memory section at Tommys.org.
For more information visit www.molarpregnancy.co.uk